Saturday, July 30, 2011

Profound Negative Impacts

Trees are dying so quickly that I am weary of taking their pictures and writing the same thing over and over. Eventually people will have to notice - or they will refuse to see. One thing I am sure of. Once people do see that ALL the trees are dying, two unavoidable implications will swiftly follow - it's air pollution; and we can't live without them.

This giant stand of Joe-Pye weed is growing where a meadow meets the woods. Butterflies and bees clustered around the tall flowers.

This week our illustrious governor in New Jersey was rushed to the hospital. I hadn't realized he had asthma, so I left this comment on the Star Ledger story about it (anyone who already knows about ozone can scroll past the shaded part to new links!

Asthma is an epidemic - so is cancer, emphysema, heart disease and diabetes. All of these conditions are caused by air pollution from burning fuel. It seems that our society has made the de facto decision that a certain percentage of the population is expendable in order for us to live lavishly with no thought for future generations that will have to contend with ever-increasing violent weather events from a destabilized climate. It's amazing that right-wing ideologues like Christie and David Koch, who had cancer, are such rigid adherents to their free-market fantasy that they don't even recognize that treating the atmosphere like an unregulated sewer is potentially lethal.

Even worse is the fact that air pollution is more toxic to vegetation than it is to people. The inexorably rising levels of tropospheric ozone, which travel across continents and oceans, interfere with photosynthesis, and cause annual agricultural crops to be stunted in growth, reducing yield and quality by billions of dollars around the globe.

Trees and other longer-lived plants that are exposed to damage season after season are dying at a rapidly accelerating rate. It has been demonstrated in research and well documented that exposure to ozone increases the susceptibility to insects, disease and fungus. Don't believe trees are dying? Go look at some - the crowns are thin, leaves are losing color from chlorosis, they are wilted, branches are breaking, bark is corroded with fatal cankers, splitting and oozing and falling off. Conifers are dropping needles and becoming transparent.

Trees are the foundation of the terrestrial ecosystem, and they are disappearing, just like corals in the acidifying oceans. It's too late to stop catastrophic climate change, but if we make drastic efforts to conserve energy we just might be able to save the species that we depend on for food and the very oxygen we breathe - never mind lumber, paper, nuts, fruit, shade and wildlife habitat.

Directly across the street the oldest trees are dead.

Even though research has shown that trees damaged by exposure to ozone are more susceptible to insects, almost all professional foresters and scientists stubbornly continue to attribute the undeniably catastrophic decimation of pines in the American and Canadian west to warming temperatures. For instance, a news story in the Washington Post just reported that the Fish & Wildlife Service is predicting the extinction of the Whitebark Pine, in the American and Canadian West, due to, let's see, white pine blister rust, fire patterns, global warming and, in the case of the 800 year old specimen below, pine bark beetles - with nary a glancing mention of the decades-long unremitting exposure to ozone!

"Logan added that he and colleagues began modeling how climate change would threaten Western tree species such as the whitebark pine in the early 1990s, but 'no one had any sense that it would be as dramatic and catastrophic as it has been.'”

Could that possibly be because they somehow forgot to factor into their models the impacts of air pollution??

Now let's look at a study which indicates there is, indeed, more afoot than indigenous beetles run amuck from a few degrees of warming, published in 2004. Here's the abstract of the paper:

Four years of severe drought from 1999 through 2003 led to unprecedented bark beetle activity in ponderosa and Jeffrey pine in the San Bernardino and San Jacinto Mountains of southern California. Pines in the San Bernardino Mountains also were heavily impacted by ozone and nitrogenous pollutants originating from urban and agricultural areas in the Los Angeles basin. We studied bark beetle activity and bark beetle associated tree mortality in pines at two drought-impacted sites in the San Bernardino Mountains, one receiving high levels of atmospheric pollutants, and one with more moderate atmospheric input.We also investigated the effects of nitrogen addition treatments of 0, 50 and 150 kg N ha-1 year-1 at each site.

Tree mortality and beetle activity were significantly higher at the high pollution site. Differences in beetle activity between sites were significantly associated with ozone injury to pines, while differences in tree mortality between sites were significantly associated with both ozone injury and fertilization level. Tree mortality was 9% higher and beetle activity 50% higher for unfertilized trees at the high pollution site compared to the low pollution site. Tree mortality increased 8% and beetle activity increased 20% under the highest rates of nitrogen additions at the low pollution site.

In a healthy forest, the distribution of bark beetles and pathogenic fungi is typically limited to a few stressed trees. Bark beetle activity on weakened trees results in scattered tree death which can increase habitat complexity for wildlife, reduce tree crowding, create canopy openings and promote plant diversity. However, stresses such as drought and air pollution can contribute to reduced tree resistance to beetle attack, and many trees in a stand could be affected. Consequently, many trees may become susceptible to beetle colonization and large-scale tree mortality could be an outcome.

So fancy that! Inspired, I discovered that even more turns up in a google search for bark beetles + ozone, which I've been wondering about lately, because it occurred to me that if the epidemic were merely temperature-related then the range of beetle damage should be distinctly correlated with both altitude and latitude. I still haven't found anything about that, but in any event I guess maybe the intertubes are getting better and better, because every time I go back and look for information there is far more available than when I first started learning about the toxicity of ozone.

In fact it boggles the mind that from skimming through the bibliographies, there seems to have been so much more published on ozone's impacts on vegetation prior to the early 2000's. Where is the more recent work? Since ozone levels have been going up and up, the impacts must be worse and worse, and yet there seems to be less interest on what is an existential threat to ecosystems and agricultural crops. One google book linking ozone to the beetle which was first published in 1997, "Forest decline and ozone: a comparison of controlled chamber and field experiments", had an exciting chart:

And a very familiar sample of leaf damage:

Even better is this treasure, a book published in 1999, "Environmental Pollution and Plant Responses". The only section I can find to read online is Chapter 9, "Effects of Tropospheric Ozone on Woody Plants" but that was quite enough to glean some very pertinent information, which will follow. (I couldn't copy and paste so I re-typed every word, leaving out the footnote numbers.) But first a few pictures for comparison's sake....My little katsura, which looked rather well in early June:

The leaves were a cool bluish-green.

By the beginning of July, the inner leaves were turning yellow.

This is chlorosis from impaired ability to photosynthesize and produce chlorophyll.

By this week all the yellow leaves had fallen onto the ground.

In early June the maple had a few spots on the leaves.

And by early July they were badly mottled.

The trunk - which should be smooth and seamless - was already lacerated when the summer began.

The bark began oozing.

It is corroded, splitting and marred with lichen.

Following are photos of fairly typical local trees, and those excellent excerpts from Chapter 9. I underlined my favorite parts and added some comments (not shaded).

Tropospheric O3 has long been defined as a phytotoxin. Much plant physiological research has been conducted in recent years on the reaction of woody plant species to tropospheric O3. Ozone has been suggested to cause the greatest amount of damage to vegetation as compared with any gaseous pollutant and its relative importance may still increase because of the decline in the occurrence of other air pollutants. Furthermore, O3 is considered as the most widespread of all atmospheric air pollutants. Many studies show that ambient O3 concentrations are potentially high enough to cause significant reductions in growth and yields of agricultural crops and trees. In this chapter, the overall responses and reactions of woody plants to tropospheric O3 levels are discussed at different hierarchical levels of organization based on an extensive, recent literature review. Furthermore, the variation in response to O3 among different genera and the interactions with other biotic and abiotic factors are documented.

These underlined sentences are of crucial import because they make it clear that we need look no further for an explanation as to why trees are dying at a rapidly accelerating rate - particularly in light of the corollary that plants damaged by ozone are more likely to be killed off by opportunistic attacks from insects, disease or fungus.

9.4.1 Ozone Uptake: Role of Stomates

Oscillations in gas exchange have also been measured in response to O3, and this is attributed to loss of stomatal control and an uncoupling of the relationship between photosynthesis and stomatal conductance. This results in a disturbed water balance, reduced ability to control water loss, and higher sensitivity to drought. Accordingly, reduce water use efficiency has been reported in response to O3....

A loss in canopy carbon gain will not only result from loss of photosynthetic capacity by individual leaves, but to a greater or lesser extent by a decrease of photosynthesizing leaf area caused by accelerated leaf shedding.

So why don't climate scientists think ozone damage to trees from ozone is an important feedback effect?

9.4.5 Leaf Level: Visible Injury and Leaf Senescence

The appearance of characteristic lesions on the leaves, chlorosis, bleaching, and accelerated abscission of leaves have long been known to be associated with elevated O3 levels. These signs of damage by O3 are observed especially on older and mature leaves.

Ozone-induced visible injury frequently is used to assess forest damage, although the extent of foliage injury does not necessarily correlate with physiological damage or reductions in growth....Biochemical and physiological injury may occur before the appearance of any visible symptoms. Acute ozone stress will generally result in visible symptoms, but low concentrations over long periods may lead to hidden damage without the appearance of visible foliar injury.

In many tree species O3 stimulates senescence processes. Natural senescence is characterized by a controlled degradation of cellular and leaf functions during which cellular constituents are remobilized before abscission. Lippert et al demonstrated high nitrogen (N) losses for beech after O3 exposure due to inhibited N-translocation before leaf drop, which differs from natural autumnal senescence where N is withdrawn from the leaves. Similar results were reported for birch. Ozone-induced degradation of leaves should therefore not be confounded with natural senescence, as it seems more like an unregulated degradation than an accelerated natural senescence.

In between the following sections are photos from Chicago - granted, climate change is making for more frequent and more violent storms...but look at how thin the trees are!

Chlorosis is not a primary result of O3 exposure, but a secondary effect due to impaired photosynthetic capacity. When chlorophyll molecules are arranged structurally in thylakoids, they are very resistant to direct oxidation, and chlorosis more likely is associated with accelerated senescence than with direct effects of O3, or its oxidative products.

For several poplar hybrids exposed to O3, visible effects on stems have been reported. Where leaves were shed, lesions or intumescences appeared on the stems, resulting in bark cracking and the exposure of soft cortical tissue. It has been hypothesized that ethylene is possibly responsible for the induction of these stem lesions.

There have been very few reports on the effects of O3 on overall tree structure. In birch and European aspen the crown structure was altered significantly after exposure to elevated O3 levels while in interamerican poplar hybrids, a lowered branchiness has been observed.

(In other words there has been hardly any study as to what happens to overall tree structure.)

9.4.6 Carbon-Allocation and Below-Ground Responses: Tree Level

Ozone causes reduction in carbon uptake by reduction of photosynthesis and of photosynthetic leaf area. The subsequent translocation of carbon to different plant organs and to different pools can also be altered by O3. In many tree species carbon retention is increased in the leaves and consequently carbon allocation to the roots is reduced. Very often, the shoot/root ratio increases following O3 exposure, due to higher reductions in root growth than in shoot growth.

(No wonder so many are falling over.)

This higher retention of C in the leaves may be explained by higher carbon demands for repair of damaged foliage, by reduced assimilate transport in the phloem, or by decreased phloem loading. In loblolly pine needles a decreased partitioning of assimilated carbon into starch and protein, and an increased partitioning into organic acides, lignin, plus structural carbohydrates, and lipids plus pigments has been reported after O3 exposure.

It is the ability to produce phloem that protects the tree from insect infestations.

This shift in partitioning from storage compounds to soluble carbohydrates and carbon compounds involved in repair might be a compensatory response to maintain photosynthetic rates. Effects on the amounts of foliar starch are sometimes contrasting, since both increases and decreases have been reported. Further research is needed to elucidate the mechanisms underlying the effects of O3 on carbohydrate metabolism....

Reduced root growth can alter the functioning of rhizosphere organisms and could make trees more susceptible to drought or nutrient deficiency. Andersen et al. reported lower carbohydrate levels in new roots of ponderosa pine seedlings after O3 exposure, which may result in reduced plant growth over time. In addition, O3 exposure during one year resulted in less new root growth in the year following exposure (carryover effect).

9.5.1 Interactions between ozone and other Abiotic and Biotic Factors

Ozone can alter the response of trees to biotic stresses. Damage due to O3 may change their tolerance or resistance to insect herbivores and plant pathogens. In general, O3 exposure has shown to increase palatability, increase herbivorous consumption, and enhance insect performance. In addition to increased susceptibility to invasion by plant pathogens, inhibitory effects of O3 against microorganisms and fungi have been reported as well. Mycorrhizae have been shown to offer beneficial effects in ameliorating O3 stress, while O3 can have negative effects on mycorrhizal development. A decrease in photosynthesis and carbon allocation to the roots would imply less carbohydrates available for the mycorrhizae.

(Maybe this is why the morels and chanterelles, which I used to collect by the sackful, are gone.)

Conclusion:

Tropospheric O3 has profound negative impacts on the growth, development, and productivity of many plants and vegetations, including trees and forests. Significant effects of O3 have been observed on a wide range of characteristics such as early leaf senescence, decreased photosynthetic assimilation, altered stomatal behavior, decreased growth and productivity, and reduced carbon allocation to roots. Although related species or genera may show very different responses to O3, and there may be large differences in sensitivity between different cultivars or clones of the sames species, the initial mechanism of O3 induced stress on plants is uniform.

("...is uniform" means that NO form of vegetation is immune - all are affected. Think about that.)

A better understanding of the effects of O3 and O3-derived oxidants is necessary for a more-detailed insight into the impact of O3 on plant growth and development. As rising tropospheric O3 levels are likely to be a continuing problem, overall growth and yield of trees and forests may be increasingly affected. In particular, the responses of trees to increased tropospheric O3 levels in combination with other environmental changes will play a very important role in determining growth, development, survival, and abundance of individual plants as well as plant communities in the future.

In light of that research should it be surprising that an article reports that traditional food sources for the First People of the Pacific Northwest are diminishing, including the roots of plants they rely upon in their diet? They too blame climate change, no doubt not realizing - because who is warning them? - that air pollution reduces the size of plant roots.

"Lewis says he's also hearing from tribal women that the roots they harvest for ceremonies are changing, too.

'They are very small, and their numbers are dwindling, as well. So, it affects a lot of our roots today, this climate change.'"

Certain to make the right wing froth at the mouth (and if you want a really good laugh, read Matt Taibbi's hysterically funny analysis of Michele Bachmann's Holy War) a new paper "Ongoing Biodiversity Loss and the need to move beyond protected areas: a review..." about the dreadful and accelerating rate of species extinction (...and why wouldn't they be? When their habitat and source of food is disappearing!) specifically links human overpopulation as the cause, going though all the reasons that nothing else other than population "stabilization" will be sufficient to address the problem:

Practical issues include budget constraints, conflicts with human development, and a growing human population that will increase not only the extent of anthropogenic stressors but the difficulty in successfully enforcing protected areas. While efforts towards improving and increasing the number and/or size of protected areas must continue, there is a clear and urgent need for the development of additional solutions for biodiversity loss, particularly ones that stabilize the size of the world’s human population and our ecological demands on biodiversity.

They conclude:

...In our view, the only scenario to achieve sustainability and to resolve the ongoing loss of biodiversity and its underlying causes will require a concerted effort to reduce human population growth and consumption and simultaneously increase the Earth’s biocapacity through the transference of technology to increase agricultural and aquacultural productivity (our Fig. 4, Kitzes et al. 2008). The fact that human population growth may also lead to economic (e.g. high competition for and/or shortages of jobs;Becker et al. 1999) and societal (e.g. shortages of food and water, lack of universal primary education, increase in communicable disease, etc.; Campbell et al. 2007) problems suggests that targeting human population growth directly would be worthwhile and could become more effective if advocated simultaneously from social, economic and ecological perspectives.

Apart from continuous growth being ecologically untenable, the negative economic effects of population growth need greater recognition. Independent of whether the human use of natural resources is theultimate driver of biodiversity loss, it is clear that the range, and growing seriousness, of human threats istoo great to be addressed through creation of more PAs (Protected Areas). The inexorable and steep loss of biodiversity and the fact that it is leading to the irreversible loss of many species suggest that we cannot afford much delay before choosing the right solution to this problem.

And now, for therapy, here is an extraordinarily beautiful video of vibrant life in the sea.

Actually, they only look "decent" because you are looking at layers and layers of trees from a distance, so it appears to be dense. If you walk up to them and look individually, the crowns are transparent, they all have broken branches, holes in their trunks, and the leaves are damaged.

This article is pretty silly really. You're attempting to attribute just about every tree problem to one thing: Ozone. You could have just as easily chosen to replace the subject of your article with acid rain and it would be just as convincing and you could make just as many arguments.

Acid rain is a huge problem. But I don't think it underlies the current rapid decline, because trees in nurseries and annual ornamentals in pots that are in enriched soil have exactly the same degree of damage to their foliage as trees growing in the ground. Also, the damage to trees in the ground is remarkably uniform. I would expect acid rain to be much more localized due to differences in altitude, soil types, etc.